Process for composite polymer beads

Abstract

A process of incorporating non-polymeric particulate matter such as magnetic materials, pigments and minerals, into a cross-linked styrene-based polymeric matrix, which process comprises dispersing the non-polymeric particles with a polymeric dispersant in a medium containing one or more vinyl monomers and a crosslinking agent, and adding a polymerization initiator. Typical polymeric dispersants are copolymers, styrenes and tertiary-nitrogen-containing vinyl monomers. Non-polymeric particulate matter incorporated into polymeric beads by this process is resistant to chemical attack and the beads may be used to prepare composite adsorbents or ion exchange resins.

We claim: 
     
       1. A process of incorporating non-polymeric magnetic particulate matter into a polymeric matrix so as to obtain composite particles or beads comprising the non-polymeric magnetic particulate matter coated or embedded in said matrix, said process comprising the steps of polymerizing while stirring a mixture of (1) a dispersion of the non-polymeric magnetic particulate matter in a medium comprising one or more vinyl monomers selected from the group consisting of styrene, substituted styrenes and vinyltoluenes, a polymeric dispersant selected from the group of copolymers consisting of styrene/2-vinylpyridine, styrene/4-vinylpyridine, styrene/vinyltrimethoxysilane and styrene/vinyltriethoxysilane, a cross-linking agent and a polymerization initiator, and (2) an aqueous phase containing a suspension stabilizer, to obtain said composite particles or beads and then separating said particles or beads from the polymerization medium; the weight ratio of non-polymeric magnetic particulate matter to the polymeric dispersant being in a range from 12:1 to 5:1; and the weight ratio of polymeric dispersant to vinyl monomers being in a range from 1:5 to 1:20. 
     
     
       2. A process according to claim 1 wherein the magnetic particulate matter is selected from the group consisting of ferrites and chromium dioxide. 
     
     
       3. A process according to claim 3 wherein zircon particles are also used with the non-polymeric magnetic particulate matter. 
     
     
       4. A process according to claim 3 wherein the non-polymeric magnetic particulate matter comprises γ-iron oxide. 
     
     
       5. A process according to claim 1 wherein the copolymer contains from 80 to 97% w/w of styrene. 
     
     
       6. A process according to claim 1 wherein the crosslinking agent is divinylbenzene. 
     
     
       7. A process according to claim 1 wherein the non-polymeric magnetic particulate matter is coated with polymeric dispersant prior to the addition of vinyl monomers and crosslinking agent. 
     
     
       8. A process according to claim 1 wherein the suspension stabilizer is polyvinyl alcohol. 
     
     
       9. A process according to claim 8 wherein the weight ratio of organic phase is in a range from 1:5 to 1:20. 
     
     
       10. A process according to claim 9 wherein the weight ratio of organic phase to aqueous phase is in a range from 1:10 to 1:16.